The present invention relates to an injection nozzle for injecting fuel into a combustion chamber of an air-compressing fuel-injection internal combustion engine. The nozzle has a diaphragm acting as a valve closer in the nozzle body. The diaphragm is liftable from its valve seat against a spring closing force as a function of injected-fuel pressure prevailing in a pressure chamber in the nozzle body to clear a spray hole leading toward the combustion chamber.
Injection nozzles of this general type are known. Nozzle needles are provided as valve closing members which open against the flow direction of the fuel. The opening lifting movements of these nozzle needles are limited by stops. This results in a constant spraying cross-section at least in the upper load range at varying speeds of the internal combustion engine. Since leakage cannot be avoided in injection nozzles of this type, complicated fuel-return systems are necessary.
An object of the present invention is to avoid the above-mentioned disadvantages and to provide an injection nozzle as a single-jet nozzle which is technically uncomplicated and has a small overall height. Another object is to provide an injection nozzle making possible a variable spraying cross-section adapted to the speed of the internal combustion engine, which also provides an approximately uniform spraying quality.
This and other objects are achieved in the present invention by providing in an injection nozzle a diaphragm that is a conical spray plug that is reoeived in a spray hole when the diaphragm is in the closed position. The nozzle includes an enclosed fluid which is under pressure when the diaphragm is in the closed position for applying the closing spring force.
An injection nozzle which can be produced inexpensively, works free of leaks, is of low construction and has a self-adjusting spraying cross-section results from constructions according to preferred embodiments of the present invention. A conventional steel spring or a fluid, namely a dilatant liquid or a non-dilatant liquid with a certain portion of gas, is used as a closing spring for this injection nozzle in preferred embodiments. In a further preferred embodiment, the diaphragm of the injection nozzle is designed as a closing spring.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.